Method of manufacturing a reinforced liner



April 20, 1965 D. M. HOFF METHOD OF MANUFACTURING A REINFORCED LINEROriginal Filed July 18, 1960 2 Sheets-Sheet 1 IN VEN TOR. DEEP/N6 M.HOFF April 20, 1965 D. M. HOFF 3,179,023

METHOD OF MANUFACTURING A REINFORCED LINER Original Filed July 18. 19602 Sheets-Sheet 2 INVENTOR. DEEP/N6 M. HOFF ,4 TTORNEYS United StatesPatent 3,179,023 METHOD OF MANUFACTURING A REINFORCED LINER Deering M.Hoff, Lafayette, Calif., assignor to Weyerhaeuser Company, Tacoma, Wash,a corporation of Washington Original application July 18, 1960, Ser. No.43,538, now Patent No. 3,094,266. Divided and this application Nov. 13,1962, Ser. No. 237,085

Claims. ((31. 93-1) This invention relates to the method ofmanufacturing a reinforced liner, and more particularly relates to themethod of manufacturing a liner having reinforced sections in which thefold lines for corrugated cartons or t greater damage to the cartonuntil the contents become seriously damaged.

An obvious solution. to this problem would be to use stronger, heaviercartons, but this would increase the expense unduly. Similarly, applyinga strip of tape or the like along the fold lines would be a workable butexpensive and probably time-consuming answer. The invention disclosed inmy co-pending application reinforces the fold lines without using anyextra material and without weakening the overall strength of the carton.The present invention contemplates a method of and means formanufacturing said car-ton. The present invention may be carried out in:a conventional box-making plant without the addition of expensivemachinery and without appreciably slowing the speed of manufacture.

An object is to provide a method and means of strengthening the'foldlines of a corrugated container by doubling over a portion of one of theliners so that a doubled thickness of such liner is provided along andon each side of the fold line where needed to strengthen the fold lineagainst failure.

Other objects and advantages will become apparent in the course of thefollowing detailed description.

In the drawings, forming a part of this application, and in which likeparts are designated by like reference numerals throughout the same,

FIGURE 1 is a generally schematic, elevational view illustrating themethod by which cartons of the present invention may be made.

FIGURE 2 is 'a plan view of the apparatus shown in FIGURE 1.

FIGURE 3 is a perspective .view'of .a fragment of a carton illustratingthe manner in which the horizontal fold lines between the side wall andtop and bottom flaps are reinforced.

FIGURE 4 isa sectional view of a carton-further showing the manner inwhich the fold lines are reinforced and with the thicknesses of thelines exaggerated for pur poses of illustration. f

FIGURE 5 is a perspective View of a portion of a car-ton illustratinganother tion.

FIGURE 6 is a perspective View of yet another type of reinforcedconstruction.

Referring now to the drawings, FIGURE 3 shows a portion of a corrugatedshippingcontainer ltl formed .glue from being applied to the corethereat.

type of reinforced construc- 3,179,623 Patented Apr. 20, 1965 from ablank having a corrugated core -11 and inner and outer liners 12 and 13glued to the core. The illustrated portion of the container has a sidewall panel 14 and adjoining top and bottom flap panels 16 and 17 joinedto the side wall panel by fold lines 18 and 19, respectively.

The inner liner 12 of the top flap 16 has a portion 21 thereof doubledback onto itself along a score line 22 and extends back down past foldline 18 so that a double thickness of this line is formed at fold line18 and on each side of this fold line. Preferably the width of thedoubled back portion 21 is approximately twice the distance from foldline 18 to score line 22 so that there will be equal widths of thedoubled thickness of liner 12 above and below fold line 18.

The inner liner 12 of the bottom ilap has a portion 23 similarly doubledback onto itself along a score line 24 to reinforce the container foldline 19. The folded back portions of liner 12 of course expose the ribs25 of the corrugated core 11.

FIGURES 1' and 2 illustrate the method by which the reinforced foldlines 13 and 19 of container 10 are produced. Since all of the apparatusused in the pres ent invention is conventional in paper bag and cartonmanufacture such apparatus is here shown only schematically. The innerliner 12 is fed forwardly as a continuously advancing web from supplyroll 26 through scoring and slitting knives 27 and 28, respectively. Thescoring knives 27 cut score lines 22 and 24 into the web on the lowerside thereof, and the slitting knives out completely through the web,forming slit lines 29 and 30 dividing the web into three strips a, b andc.

The web then passes under glue rollers 31 which apply glue from the gluepct 32 to theweb. These rollers form glue strips 33 having a widthgenerally equal to the distance between the score lines 22 and 24 andthe slit lines 29 and 30 and extend generally from the score linestowards the center of the web.

The center strip b of the web then has its outer edge portions 21 and 23passed through folding shoes 34 which bends the edges upwardly aroundthe score lines 22 and 24 and folds them back onto the upper surface ofthe center web strip, thus forming double thicknesses at the edges ofthis strip. Pressure rollers 36 press the doubled portion of the webtogether so that the gluetherebetween will hold them together.

In the meantime, webs of the corrugated core 11 and the outer liner .13will have been glued together and will have been fed to the glue roller37 to have glue a plied to the exposed surface of the core web. Glueroller 37 rotates through glue pot 38 and then against acounter-rotating doctor roll 39 to wipe off excess glue thereon. Inorder to leave unglued strips on the core surface, thin metal strips 40of a width corresponding to the width of the gaps between the strips a,b and c of liner web 12 are brought around the upper surface of glueroller 3-7 and are secured by screws or other suitable means to thewalls of the glue pct 38. The

' interposing of the metal strips 40 between the glue roller and thecorrugated core surface of course prevents any The width of the metalstrips 46 and the distance thereof from the ends of the glue roller 37are easily adjusted.

The inner liner web 12 is now brought into registering engagement withthe glued surface of the corrugated core web 11 and the webs are pressedtogether by pressure rollers 41. The Unglued strips of the core webcoincide with the gaps in liner web 12 between the .center strip b whichforms carton blanks having the desired size side wall panels and top andbottom flap panels and in which all panels are connected together byfold lines so that the cut and creased carton blanks can be easilyerected into cartons for use.

The fold lines 18 and 19 between the side walls and the top and bottomflaps will be made by the blank forming apparatus parallel to the sideedges of web 12 and will be formed in the middle of the doubled overportions of web strip 11, as shown in FIGURE 3. It has been foundsatisfactory for a carton having side walls of approximately 12 inchesin height to have the doubled over portion of the web 12 extendapproximately one inch on each side of the fold lines 18 and 19.

If it is desired to form a different shape carton from webs 11, 12 and13 such that the fold lines 18 and 19 are nearer or farther apart, it isa simple matter to move the scoring knives 27 and the slitting knives 28nearer up, as shown in FIGURE 1.

together or farther apart and to adjust the distance bebetween layers ofcontainers when stacked on top of each other.

The embodiment of FIGURE 5 is manufactured by essentially the sameprocess as previously described. As shown in FIGURE 5, the portion 21aof the outer panel 13a is folded back around score lines 22a and awayfrom the corrugated core 11a rather than being folded into and againstthe core as in FIGURE 3. This last detail of folding is a matter ofdesign and illustrates how the embodiment shown in FIGURE 3 can bevaried if so desired to produce this manner of folding. The foldingshoes 3 will of course have to be reversed so as to fold the edges ofthe central part of the Web down rather than The scoring knives 27 andglue rollers 31 would also have to be reversed to operate on the otherside of the web.

FIGURE 6 shows yet another embodiment of the carton which has beendeveloped for use in packing such items as lettuce, for example. Theseitems will not stack within a carton and will exert outward pressure onthe side walls as the carton is packed and when the cartons are laterpiled on top of one another. In addition, the top flaps are unusuallyinterlaced rather than being glued or stapled, and thus no support isgiven the side walls by same time so that they will register with thespaces be- I tween web strips a and b, and b and c.

As is apparent from the above, the carton 10 will be formed havingreinforced fold lines 18 and 19, which will be much more resistant tocutting by can rims, without increasing the amount of material used inthe carton. The

resistance of the inner liner to can rim cutting will be The top andbottom flaps which have a portion of the single thickness side walls.Thus, the carton has its weakest points reinforced without requiring anyadditional material and without weakening the carton as a whole.

The carton is additionally strengthened against endwise or sidewiseforces applied thereto due to the channel effect of the doubled backliner portion. As will be noted in FIGURES 3 and 4, the doubled backportions 21 and 23 of the inner liner 14 form double thickness L-shapedchannels along the upper and lower fold lines when the carton is inerected position. Thus, when any one of the side walls is subjected toend-to-end compression, the channeled shape of the reinforced fold lineswill greatly rigidify the carton.

The apparatus used for cutting, folding and gluing the doubled overportions can be readily set up on conventional carton forming machineryand without any appreciable decrease in speed of conventionaloperations.

FIGURE 5 illustrates a modification of the carton in which the carton10a is formed with side walls 14a and top flaps 16a from a blank havinga corrugated core 11a and inner and outer liners 12a and 13a glued tothe core. In this modification, the outer liner has a portion 21athereof doubled back onto itself along score line 22a so that a doublethickness of the outer line 13a is formed along the length of the foldline 18a and on each side of this fold line. I

The lower fold line between the side walls and the bottom flaps (notshown) is similarly formed. In this embodiment, the ribs 25a of thecorrugated core will be partially exposed on the top and bottom of thecontainer 10a when it is filled and closed and will reduce the slippagethe top flaps. As a consequence, the weakest points of the carton arethe vertical fold lines between adjacent side panels. The presentembodiment has been designed specifically to strengthen the upperportion of the vertical fold lines to prevent the carton from splittingalong these lines. It is not necessary to strengthen the entire heightof these fold lines since it is only necessary to prevent the fold linesfrom starting to tear, and invariably this failure starts from theunsupported upper end.

The carton 10b, shown in FIGURE 6, is again formed with side walls 141)and top flaps 1617 from a blank having a corrugated core 111) and innerand outer liners 12b and 13b glued thereto. In this embodiment, aportion 21!; of the inner liner of the side walls is folded back alongscore line 22b and extends to the horizontal fold lines 18b between theside walls and top flaps. This then forms a double thickness of theinner liner at the vertical fold line 20b between adjacent side wallpanels which double thickness extends down from the top thereof down tothe score line 22b. Since most of the peripheral strength of the cartonis derived from the tensile strength of the liners at the vertical foldlines it is obvious that the doubled thickness of a liner results indouble strength thereof.

The changes in the manufacturing setup of FIGURE 1 to produce the FIGURE6 embodiment will be readily apparent. Only one scoring knife 27 and oneslitting knife 28 will be needed, and the folding shoe 34 will have tobe reversed so as to fold the inner edge of web strip a around the scoreline formed in web strip a. Of course, the glue roller 31 and pressurerollers 36 will have to be shifted to operate on web strip a.

If desired, a thin strip of additional reinforcing such as steel tape orthe like could be inserted between the doubled-over portion of the innerliner 12b during the steps of manufacture thereof. For example, thisstep could be performed after the application of the glue strip 33 andbefore the folding over by the folding shoes 34.

Although the above description has been directed to the folding back ofportions of the liner Web 12, it is of course to be realized that theother liner web 13 could be similarly operated upon by similar equipmentbefore it is glued to the corrugated core. Further, either one or bothliners could be so reinforced depending upon the results desired. Forexample, if it were desired to reinforce the fold lines on both theinside and outside of a carton both liners would be folded back toreinforce the desired area. Or, one liner could be folded back toreinforce one particular area and the other liner could be folded backto reinforce another desired area, again depending upon the particularresults desired. It is also to be realized that folding shoes 34 arereadily available to form triple or quadruple folds, and it is intendedthat these could be used for the purpose described in this application,if so desired.

A further operation which can be performed by conventional box-makingapparatus, if desired, is to spray the exposed strips of the corrugatedcore with waterproofing solution to prevent core failures in the eventthat moisture is to be encountered in the use, storage or handling ofthe cartons.

Although the invention has been shown as used with corrugated shippingcartons it can also be applied to articles made from solid fiberboardwherein the liner is doubled back to provide a greater localizedstrength. In addition, the invention finds applicability in other usesof corrugated articles wherever localized stresses are encountered. Ofcourse, in such use, the stress must be such that the gap in the liner,resulting from doubling over a portion thereof, does not unduly weakenthe article.

It is to be further realized that the forms of the invention hereinshown and described are to taken as preferred embodiments of the sameand that various changes may be made in the shape, size and arrangementof parts without departing from the spirit of the invention or the scopeof the attached claims.

I claim:

1. In a method of making corrugated containers, the steps ofcontinuously advancing a web of liner material, slitting said web alonga line parallel to the edge of said web, scoring said liner along a lineparallel and closely adjacent to said slit line, gluing said webadjacent said score line, folding said web adjacent one side of saidslit line onto itself along said score line to adhere the web to itselfand form a double thickness of said liner web and leaving a gap betweenthe folded and unfolded portions of said liner web equal to the width ofsaid double thickness portion, continuously advancing a web ofcorrugated core material, gluing one surface of said core web whileleaving a lengthwise strip of said one surface unglued, bringing theliner material web into engagement with the glued surface of said corematerial web with the gap in said liner web coinciding with the ungluedstrip of said core web and subsequently scoring said material along saiddouble thickness portion.

2. In a method of making corrugated containers, the steps ofcontinuously advancing a plurality of Webs of liner material, gluing atleast one of said webs longitudinally of said web, folding at least oneside of said web onto itself with said glue being between said foldledweb portions to form a double thickness portion of said liner web, saiddouble thickness portion being adjacent one of the other of saidplurality of webs and being spaced from said adjacent Web a distanceequal to the width of said double thickness portion, continuouslyadvancing a web of corrugated core material, gluing one surface of saidcore web While leaving a lengthwise strip of said one surface unglued,and bringing the liner material webs into engagement with the gluedsurface of said core material web while maintaining said space betweensaid double thickness portion and said adjacent Web and aligning saidunglued strip of said core web with said space, and subsequently scoringsaid material along said double thickness portion.

3. The method of claim 2 in which said plurality of Webs comprises atleast three webs.

4. The method of claim 3 in which at least one of said edges of saidcenter web is folded.

5. The method of claim 3 in which the inner edge of at least one of saidside webs is folded.

References Cited by the Examiner UNITED STATES PATENTS FRANK E. BAILEY,Primary Examiner.

1. IN A METHOD OF MAKING CORRUGATED CONTAINERS, THE STEP OF CONTINUOUSLYADVANCING A WEB OF LINER MATERIAL, SLITTING SAID WEB ALONG A LINEPARALLEL TO THE EDGE OF SAID WEB, SCORING SAID LINER ALONG A LINEPARALLEL AND CLOSELY ADJACENT TO SAID SLIT LINE, GLUING SAID WEBADJACENT SAID SCORE LINE, FOLDING SAID WEB ADJACENT ONE SIDE OF SAIDSLIT LINE ONTO ITSELF ALONG SAID SCORE LINE TO ADHERE THE WEB TO ITSELFAND FORM A DOUBLE THICKNESS OF SAID LINER WEB AND LEAVING A GAP BETWEENTHE FOLDED AND UNFOLDED PORTIONS OF SAID LINER WEB EQUAL TO THE WIDTH OFSAID DOUBLE